International Journal of Environment, Agriculture and Biotechnology Vol-6, Issue-1; Jan-Feb, 2021
Journal Home Page Available: https://ijeab.com/ Journal DOI: 10.22161/ijeab
LED night lighting improving mini-budding technology in Hevea brasiliensis Xing-Cheng Yao, Han-Qi Tu, Xin-Long Wang, Jun Wang*
Rubber Research Institute, Key Laboratory of Biology and Genetic Resources of Rubber Tree, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101，Hainan, China *Corresponding author
Received: 27 Nov 2020; Received in revised form: 12 Jan 2021; Accepted: 21 Jan 2021; Available online: 01 Feb 2021 ©2021 The Author(s). Published by Infogain Publication. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/).
Abstract— Mini-budding, exploiting seedlings of about 20 days, is a major technology for planting material propagation of rubber tree in China. The first pair leaves should be kept on rootstocks for assimilation. Manually axillary bud picking is needed to promote scion bud germination, but it is difficult and labor intensive. In this study, topping was carried out on the position below the first pair leaves and the subsequent plants were subjected to LED night lighting. The plant growth and the plant survival rate were improved by night lighting. The scion growth of the 1st flush was not comparable to that of plants with leaves on rootstocks. The high amount of chlorophyll content in the leaf might be response for this. The plant survival rate of the treatment was similar with that of plants with leaves on rootstocks. Thus, applying LED night lighting to the plants without leaves on rootstocks improved mini-budding technology by avoiding axillary bud picking. Keywords— grafting, nursery, photoperiod, vegetative propagation, rubber tree.
I.
INTRODUCTION
(Dong et al., 1986).Therefore, the early growth of grafted
The Para rubber tree (Hevea brasiliensis Willd. Ex. A. de.
shoot is mainly controlled by the rootstock. In general, the
Juss.Müll-Arg.) is preferred over alternative sources of
larger size of rootstock, the more carbohydrate stored in
natural rubber worldwide due to the quality and quantity
the rootstock, and the stronger of germinating shoot.
of latex produced. The planting materials of rubber trees
There are several types of bud grafting according to
are vegetatively propagated by bud grafting (budding is
the
the colloquial term). The combined plants include clonal
Mini-budding(Figure 1), developed in the 1980s in China
scions and hetero-rootstocks. After grafted, the rootstock
by Huang (Huang, 1989), is carried out when the seedling
can affect the initiated growth of scion. The carbohydrate
rootstocks are as young as 2-3 weeks old. The diameter
for germination of grafted bud (scion) is directly provided
and height of seedling rootstock (graft position) is less
by the rootstock. The leaves of germinating shoots could
than 5 mm and 30 cm, respectively. One month after
not assimilate until at the stage of mid light green period
grafting, topping is carried out on the position just above
ISSN: 2456-1878 https://dx.doi.org/10.22161/ijeab.61.18
size
of
rootstocks
(Priyadashan,
2017).
135
Xing-Cheng Yao et al.
International Journal of Environment, Agriculture and Biotechnology, 6(1)-2021
the first pair leaves. The axillary buds above the grafted
and could not supply sufficient carbohydrate for the shoot
bud are removed to eliminate apical dominance. Using
(scion) grow, at least one or two leaves must be kept on the
mini-budding, planting materials could be produced as
grafted root stocks for assimilation (Figure 1-C). However,
fast as 6 months after sowing seeds in the seedbed during
manually axillary budpicking is difficult and labor
August–September. Mini-budding is preferred in China
intensive. Axillary bud picking is practiced twice or thrice
because it reduces cost of production by decreasing the
sometimesbefore axillary buds are totally picked.
time and nursery area for production of grafted planting
Therefore, it is necessary to improve topping and
materials.
subsequent axillary bud picking for mini-budding plants.
As the rootstocks for mini-budding are quite small
Fig. 1: Mini-budding profile. (A),Seedlings suitable for mini-budding. Arrow: graft position. (B),Graft finished. (C), Scion shoot germination. Arrow: axially buds have been picked. (D), Grafting in a room. ISSN: 2456-1878 https://dx.doi.org/10.22161/ijeab.61.17
136
Xing-Cheng Yao et al.
International Journal of Environment, Agriculture and Biotechnology, 6(1)-2021
Light is a key environmental factor regulating plant growth
by
affecting
photosynthesis.
Plant growth measurements
Extended
The plant height and stem (scion) diameter were
photoperiod can improve plant growth by synthesizing
monitored in May, July, September and November, 2020.
more carbohydrate. Supplemental lighting during the
The flush number and flush length were measured when
night extends the photoperiod and thus promotes plant
the experiment was finished in November, 2020. The stem
growth. Light-emitting diode (LED) lamps are the
diameter was measured at 5 cm above the shoot
preferred source for supplemental lighting due to their low
germinating position. The percentage of plant survival
operating temperature, durability and low cost (Singh et
(scion shoots that successfully grew to the stationary
al., 2015). Supplemental night lighting has been widely
phase of second flush) was calculated.
used in the production of crops and other plants to promote growth (Fukuda et al. 2000, 2004; Okushima et
Chlorophyll content analysis
al., 2012; Zhou et al., 2013; Kweon et al., 2016; Tewolde
After cutting off, the green bark of the rootstock stems
et al., 2016).
was analyzed for chlorophyll content. The green bark was
In this study, the min-budding rootstock plants were cut off on the position just below the first pair leaves (the first flush) when the plants grew to the stationary phase of the second flush. The grafted plants were then subjected to overnight LED lighting. The effect of LED night lighting on the growth of mini-budding plants was investigated.
peeled from the stems and the fresh weight of bark was measured. Approximately 0.1 g of bark tissue was ground and incubated in 20 ml of a mixture of acetone, ethanol and deionized water (4.5:4.5:1) in the dark for 24 h at 25°C. The absorptions of chlorophyll a andchlorophyll b were measured at 647 and 664 nm, respectively, using a spectrophotometer (TU-1810s, PERSEE, China). The chlorophyll content was calculated according to the
II.
MATERIALS AND METHODS
methods
of
Wellburn(1994).The
total
amount
of
chlorophyll of green bark was calculated as chlorophyll
Plant materials Hevea seeds of clone GT1 were sowed in August, 2019. Mini-budding was carried out with scion clone CATAS 7-33-97 in September. The grafted plants were planted in polybags which were placed in an arched shed with sun shade cloth. Topping was carried out in November, 2019, when the grafted rootstock plants grew to the second
content multiplying fresh weight.The chlorophyll content of the first pair leaves kept on the rootstock was also analyzed. The fresh weight of the two trifoliate leaves (without petioles) was measured. The total amount of chlorophyll of leaf was calculated as chlorophyll content multiplying fresh weight. Statistics analysis
flush. The grafted plants were cut off on the position just
The statistical analyses were performed using SPSS 22.0
below the first pair leaves. Two treatments were carried
software. Significance at the 0.05 level was determined
out and each replicated thrice. Treatment one (designated
using Tukey’s multiple range test.
as Ⅰ-LED) was subjected to LED lamp night lighting. LEDs were hung 0.5 m above the plants. The lamp spectrum
was
red
and
blue
combined
with
a
photosynthetic photon flux density (PPFD) of 200 μmol m-2 s-1 measured at 10 cm from the LED lamp. Supplemental lighting was applied during the night from 19:00 to 06:00.Treatment two (designated as Ⅱ – no LED) was subjected to no LED night lighting. The plants obtained by conventional mini-budding were used as a control. ISSN: 2456-1878 https://dx.doi.org/10.22161/ijeab.61.17
III.
RESULTS AND DISCUSSION
The diameter of seedling rootstocks was measured when mini-budding was carried out. The mean diameter was 3.51 mm at the position of 3 cm above the root collar. After cutting off on the position below the first pair leaves, the grafted plants were grown under the condition with or without supplemental LED night lighting. The plant height and stem diameter were monitored after growing 6, 8, 10 and 12 months. The plants of Ⅰ- LED exhibited larger
137
Xing-Cheng Yao et al.
International Journal of Environment, Agriculture and Biotechnology, 6(1)-2021
stem diameter and higher plant height than Ⅱ- no LED
length (figure 4). The 1st flush length of control plants
(Figure 2, 3), showing that supplemental LED night
(obtained from conventional mini-budding)was 14.35 cm,
lighting promoted plant growth.The plants of Ⅰ- LED grew
significantly longer than that of Ⅰ- LED (6.67 cm) and Ⅱ-
more flushes (mean 5.5) than that of Ⅱ- no LED (mean
no LED (5.43 cm). The stem diameter of control plants
4.6), which indicated that the rhythmic growth has been
was also larger than that of Ⅰ- LED when the shoots
accelerated. The mean flush length of plants of Ⅰ- LED
finished the first flush growth.This indicated that more
was significantly longer than that of Ⅱ- no LED (Figure 4).
carbohydrate has been assimilated by plants with leaves
The 1st,2nd, 3rd, 4th and 5th flush length between Ⅰ- LED
kept on rootstocks. Even though the grafted plants without
and Ⅱ- no LED were compared, respectively. The 3rd
leaves grew under night lighting, the carbohydrate they
flush length of Ⅰ- LED was significantly longer than that
assimilated was not comparable to that assimilated by the
of Ⅱ- no LED, but the other flushes showed similar flush
leaves in control plants.
Fig. 2: Comparison of stem diameter between Ⅰ– LED and Ⅱ– no LED.
ISSN: 2456-1878 https://dx.doi.org/10.22161/ijeab.61.17
138
Xing-Cheng Yao et al.
International Journal of Environment, Agriculture and Biotechnology, 6(1)-2021
Fig. 3: Comparison of plant height between Ⅰ– LED and Ⅱ– no LED.
Fig. 4: Comparison of flush length (FL) between Ⅰ– LED and Ⅱ– no LED.The earliest germinated flush was designated as the first flush. ISSN: 2456-1878 https://dx.doi.org/10.22161/ijeab.61.17
139
Xing-Cheng Yao et al.
International Journal of Environment, Agriculture and Biotechnology, 6(1)-2021
The plant survival rate is an important index for
greatly.
evaluating seedling cultivation technology because it affects the production cost. The plant survival rate of Ⅰ-
IV.
LED and Ⅱ- no LED was92.3% and 45.4%, respectively.
CONCLUSION
There was significant difference between Ⅰ- LED and Ⅱ-
Mini-budding is a prevalent technology for vegetative
no LED. This implied that the plants of Ⅰ- LED could
propagation of rubber tree in China. The first pair leaves
assimilate during night lighting. Therefore, more
should be kept on rootstocks for assimilation when
carbohydrate had been synthesized, which was then
topping is conducted, but the axillary bud picking which is
utilized for shoot growth. The percentage of plant survival
labor intensive must be carried out. Mini-budding plants
of Ⅰ- LED (92.3%) was comparable with that of control
without leaves on the rootstock exhibited extremely poor
plants (93.4%).This indicated thatthe mini-budding plants
growth and low plant survival rate. LED night lighting
without leaves on rootstock could provide proper
could improve the growth as well as plant survival rate of
carbohydrate for normal shoot growth when grew under
mini-budding plants without leaves on the rootstock.
supplemental LED night lighting.
Therefore,
The chlorophyll content in the green bark tissue of young rootstock was 1.77 mg g-1 FW (fresh weight), which
suggested
that
the
green
bark
could
applying
LED
night
lighting
to
the
mini-budding plants without leaves on the rootstock improved mini-budding technology by avoiding axillary bud picking.
photosynthesize. The chlorophyll content in the leaves was much higher (3.62 mg g-1 FW). The fresh weight of
ACKNOWLEDGEMENT
leaf was 3 times of that of green bark. The total
The study was financially supported by China Agriculture
chlorophyll amount in the bark tissue and the leaves was
Research System (CARS-33-YZ4).
0.97 and 5.86 mg per plant, respectively. The total chlorophyll amount in the leaves was about 6times of that REFERENCES
in the bark tissue. Therefore, the plants with leaves on rootstock can assimilate much more carbohydrate than
[1]
Dong, J. H, Li, D., He, C., Shen, Q., Tang, Y. (1986).
plants ofⅠ- LED during daytime. According to Wang et al
Relation of glycollate oxidase activity to photosynthesis
(2010)the net photosynthetic rate of CATAS 7-33-97
activity and chlorophyll content in leaves of Hevea
under PPFD 200 μmol m s was about 3~5 μmol m s ,
brasiliensis. Chinese Journalof Tropical Crops, 7(1): 1–8.
-2
-1
-2 -1
and the dark respiration rate was about 1.75 μmol m s . -2
-1
[2]
Fukuda, N., Nishimura, S.,Fumiki, Y. (2004). Effect
It indicated that the amount of carbohydrate of Ⅰ – LED
supplemental lighting during the period from middle of
synthesized during night lighting could not compensate
night to morning on photosynthesis and leaf thickness of
for the carbohydrate gap during daytime between Ⅰ- LED
lettuce (Lactuca sativa L.) and tsukena (Brassica
and control plants. This probably was thereason why
campestris L.). Acta Hortic, 633: 237–244.
control plants were stronger than plants of Ⅰ- LED.
[3]
Fukuda, N., Suzuki, V., Ikeda, H. (2000). Effects of
The size of mini-budding plants is smaller, compared
supplemental lighting from 23:00 to 7:00 on growth of
to that of green and brown budding. The plant density of
vegetables cultured by NFT. J Japan Soc Hort Sci, 69:
mini-budding plants without leaves on rootstocks during
76–83.
night lighting period wouldbe greater. Therefore, applying
[4]
propagation-mini-seedling budding. Chinese Journal of
LED night lighting will not cost too much for power
Tropical Crops, 10(1): 25-31.
energy. Axillary bud picking is labor intensive and the mean time is 45 second per one plant. However, topping
Huang, S. F.(1989). A novel approach to rubber
[5]
Kweon, H. J., Park, M. Y., Song, Y. Y., Kang, S. B.,
with a scissor on the position below the first pair leaves
Sagong, D. H. (2016). Influence of red LED treatment on
only spends 1 second per plant. There is no procedure of
photosynthesis, vegetative growth and fruit quality
axillary bud picking. Therefore, the labor cost will reduce
in'Fuji'/M 26 apple trees during night. Protected
ISSN: 2456-1878 https://dx.doi.org/10.22161/ijeab.61.17
140
Xing-Cheng Yao et al.
International Journal of Environment, Agriculture and Biotechnology, 6(1)-2021
Horticulture and Plant Factory, 25: 57–6. [6]
Okushima, L., Fukuda, N., Kanesaka, N., Sekiguchi, K., Odawara, N., Sase, S, Mito, C. (2012) Effect of overnight supplemental lighting with different spectral LEDs on the growth of some leafy vegetables. In VII International Symposium
on
Light
in
Horticultural
Systems,
956:327–333. [7]
Priyadarshan, P. M. (2017). Biology of hevea rubber. Springer, Switzerland.
[8]
Singh, D., Basu, C., Meinhardt-Wollweber, M., Roth, B. (2015). LEDs for energy efficient greenhouse lighting. Renewable Sustainable Energy Reviews, 49:39–147.
[9]
Tewolde, F. T., Lu, N., Shiina, K., Maruo, T., Takagaki, M., Kozai, T., Yamori, W. (2016). Nighttime supplemental LED inter-lighting improves growth and yield of single-Truss tomatoes by enhancing photosynthesis in both winter and summer. Frontier Plant Sciences, 7:448.
[10] Wang, J. K., Xie, G. S., Chen, B. Q. (2010). Photosynthetic characteristics of different varieties of rubber budding trees. Southwest China Journal of Agricultural Sciences, 23(6):1882–1886. [11] Wellburn, A. R. (1994) The spectral determination of chlorophylls a and b, as well as carotenoids, using various solvents with spectrophotometers of different resolution. Journal Plant Physiology, 144(3):307–313. [12] Zhou, W. L., Liu, W. K., Yang, Q. C. (2013). Reducing nitrate content in lettuce by pre-harvest continuous light delivered by red and blue light-emitting diodes. Journal Plant Nutrition, 36:481–490.
ISSN: 2456-1878 https://dx.doi.org/10.22161/ijeab.61.17
141